It was an event akin to a plot twist in one of Stieg Larsson's now ubiquitous books: journalist spends his life fighting social injustice while quietly penning a series of feminist crime thrillers, but dies of a heart attack before his literary career takes off. Not only did Larsson, at 50, die before he was able to taste success, but his death sparked a legal battle between his partner and his family for royalties from the huge sales of his Millennium trilogy (The Girl With the Dragon Tattoo and its successors). So who was the real Larsson, and what would he have made of his success?

His friend, the journalist and fellow activist Kurdo Baksi, goes some way to answering both in this short but powerful memoir. For Larsson geeks such as myself, the unearthed details of his past and the fond recollections of his ceaseless pursuit of justice are gripping. We know much about his character already: Larsson the workaholic, Larsson the campaigner for human rights, Larsson the quiet agitator, happiest fighting from the shadows. Baksi walks the line between grieving friend and impartial investigator reasonably well, though he adopts an apologetic tone when delivering details that show Larsson to be less than perfect.

For example, Larsson despised misogyny, but Baksi hints that it was his partner, Eva Gabrielsson, who "took care of everything" on the domestic front. But then comes a more disturbing clue as to why Larsson so deplored violence against women: Baksi reveals that, as a teenager, Larsson watched a group of friends rape a 15-year-old girl while he stood by, terrified. He later rang the girl to apologise for not saving her, to which she reportedly responded: "I will never forgive you." Baksi claims the images of her rape and his docile role in her attack haunted Larsson for the rest of his life.

Perhaps because of this, but also because of the devotion his mother showed as a trade union activist before her death from a brain haemorrhage, Larsson demanded very high standards of behaviour of himself and others.

Larsson, like his character Mikael Blomkvist, was an investigative journalist, but according to Baksi the similarities end there: "I think Stieg had much more in common with [Millennium heroine] Lisbeth Salander," says Baksi, "not least their lack of confidence in so-called authorities. They both had a reluctance to talk about the past. Both of them preferred not to discuss their childhood. Moreover, they appear to have had similarly bad eating habits."

So, to that second question: how would Larsson have coped with success? Reasonably well, according to Baksi. In his eyes, Larsson was already becoming more confident and expressive in the months leading up to his death, when it became clear he was on the brink of success. And the news that will break the hearts of fans: Larsson claimed to have ideas for at least 10 more Millennium books.Ultimately, Stieg Larsson, My Friend is sustenance for those still mourning the end of Salander and Blomkvist. Without more books to satisfy our collective appetite (although there are rumours of a fourth, nearly finished book) we're left to grab on to whatever we can find. In this moving, well-paced and honest account of Larsson's life, we will have to make do.